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Rafael Navarro, Jesus E. Gomez-Correa, Javier Mazzaferri; Refractive Status Of The Eye Across The 2d Visual Field As Measured By Refractive Error Sensing. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4374.
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© ARVO (1962-2015); The Authors (2016-present)
To develop an objective method for measuring peripheral refractive error and to study the refractive status of the eye across the two-dimensional ±40º visual field.
Peripheral refractive error is objectively measured at different visual angles, field (theta) and azimuth (phi), in a group of normal subjects and for near vision (3 D vergence) by the method of refractive error sensing [Navarro, JOV 10 (13):3, 2010]. Wavefront slopes are measured by a wide-angle laser ray tracing system, at different points of the pupil (hexagonal sampling) and for 21 visual field angles on a 4-branches, S, N, I and T (superior, nasal, inferior and temporal) spiral. The local refractive error is given by the wavefront curvature at each point of the pupil. In this way, we obtain three pupil maps (sphere, cylinder and axis) for each field position (theta, phi). The prescription is obtained by computing the more likely value in each map. Measurements are repeated 4 times and averaged.
Results show a wide intersubject variability and significant asymmetries between the four spiral branches S, N, I and T of visual field. Average results (15 eyes) show a moderate-to-low change of sphere, from -0.8 D at the fovea to reach a maximum, -1.5 D at about 28º in the upper visual field, and then a minimum, -0.2 D, at 40º temporal. Average stigmatism shows a nearly quadratic increase toward the periphery with the maximum, 2.2 D at 40º. The minimum value, 0.65 D was found off-axis (7º upper branch), whereas the value at the fovea, 0.85 D, is slightly higher.
Refractive error sensing is a fast, robust and fully objective method, which seems well suited for measuring the refractive status of the eye in the peripheral visual field. Results are mostly consistent with previous studies. Sphere shows significant differences between S, N, I and T fields, but the amount of peripheral astigmatism is somewhat lower than previously reported. The lowest value of astigmatism is found off-axis.
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